Knightley entered Parliament for Northamptonshire South in 1852 (succeeding his father), a seat he held until 1892. In 1892 he was raised to the peerage as Baron Knightley, of Fawsley in the County of Northampton.[2]

Lord Knightley married Louisa Mary, daughter of General Sir Edward Bowater, in 1869. The marriage was childless. He died in December 1895, aged 76, when the barony became extinct. He was succeeded in the baronetcy by his first cousin Valentine Knightley. Lady Knightley died in October 1913.[1]